New Zealand’s planted forest area is dominated by radiata pine (90%), but also includes Douglas-fir (6%), and a range of minor species including eucalypts and cypress. Carbon sequestration in planted forest is currently estimated using yield tables from the Forest Carbon Predictor (FCP), which was designed to estimate dry matter in live biomass and dead organic matter pools in radiata pine stands. Stand variables required as model inputs include basal area, mean top height, stocking, and tending regime. In addition, wood density needs to be measured or estimated. When the FCP is applied to plantation species other than radiata pine, dry matter estimates may need to be adjusted to remove bias.

Urban forests are under increased pressure from invasion by exotic (alien) species. The vegetation present in the matrix of urban sites is a rich source of alien invasive propagules, which increases the risk of alien invasion in forests within an urban space, leading to a decline in indigenous species. Therefore, determining the distribution patterns of native and exotic species as influenced by environmental factors can assist in quantifying the impact of exotic species at broad scales based on responses on a finer scale. Quantifying the effects of multiple environmental factors on the distribution patterns of both indigenous and alien species in the ecosystem may help in prescribing suitable management efforts.

Remote sensing techniques and data are becoming increasingly popular in forest management, e.g. for change detection and health condition analysis. Tree species recognition is a fundamental issue in taking forest inventories, especially in carbon budget modelling. Hyperspectral imagery provides an accurate classification results for large areas based on a relatively small amount of training data.

Saraca asoca (Roxb.) De Wilde is a valuable tree used in traditional medicine against a variety of ailments. Almost all parts of the tree are used for various commercial herbal preparations. Due to overexploitation, the species is rapidly disappearing from Western Ghats where it is native and grew extensively until recently. Conservation of this important medicinal plant is therefore an urgent need. To plan effective conservation strategies, a scientific assessment of the genetic diversity and distribution is needed.

Additional file 1 to 'Assessment of genetic diversity of Saraca asoca (Roxb.) De Wilde: a commercially important, but endangered, forest tree species in Western Ghats, India'

Elaeocarpus prunifolius Wall. ex Müll. Berol. is a threatened tree species of north-eastern India. The present study was undertaken to investigate the type of dormancy prevailing in seeds of E. prunifolius, explore seed dormancy breaking techniques and assess seedling fitness.

Buxus hyrcana (boxwood) is an endangered species in the Hyrcanian forests in the north of Iran. This tree is threatened by habitat loss but faces additional threats from the introduced disease the boxwood blight (caused by the fungus Calonectria pseudonaviculata syn. Cylindrocladium pseudonaviculatum, Cy. buxicola) and the potential effects of climate change. As wide range of genetic polymorphism is necessary to ensure successful adaptation to rapid climatic changes.

Additional file 1 to 'Evaluation of genetic differentiation among healthy and infected Buxus hyrcana with boxwood blight using RAPD and ISSR markers'

Additional file 2 to 'Evaluation of genetic differentiation among healthy and infected Buxus hyrcana with boxwood blight using RAPD and ISSR markers'

Carbon fractions are applied to dry matter estimates to calculate carbon stocks in forest stands. A default carbon fraction has been applied to planted forest species in New Zealand; however, various studies have shown that the carbon fraction can differ among species and between tree components. New Zealand-specific carbon fractions were, therefore, developed to improve the accuracy of carbon stock estimates for international reporting purposes.

Eucalyptus bosistoana is currently investigated in New Zealand for its potential to produce naturally durable timber in short-rotation plantations. Little is known of heartwood formation in young trees. The objective of this study was to identify conventional and confocal microscopy methods which allow the observation of cell organelles and the chemical composition in the E. bosistoana parenchyma cells before and after heartwood formation.

Stand density changes during forest growth. Various types and intensities of thinning operations can be applied in order to improve the volume of the remaining trees. It is not clear whether or not thinning results in better total volume increment although timber value is usually higher when thicker logs are obtained from trees. The objective of this study was to determine if Scots pine (Pinus sylvestris L.) stands of lower density would produce timber of a higher value than stands with a higher density and thinner trees. Methods: The research was carried out on 20 experimental plots in 81–90-year-old Scots pine stands, located in north-western Poland. The data obtained were used to simulate the logging of the trees into either 2.5-m logs or tree tops, which were classified into five quality classes of timber. The volume of each assortment was calculated, based on its dimensions, and the value in EUR was calculated. Results: It was found that the correlation between stand density and the total value of the wood was very weak and not statistically significant. However, taking each assortment separately, the values of sawmill wood, pulpwood and energy wood were significantly correlated with stand density. Conclusions: It was concluded that lower densities were more profitable for sawmill wood production, while higher densities might be more beneficial in biomass production.

Restoring erosion-prone land with indigenous species, whether by managed reforestation (planting) or by passive natural reversion, is reliant on knowing which species mix is likely to provide the quickest and most effective mitigation against shallow landslides. In turn, this requires knowledge of differences in growth metrics among plant species, particularly during their formative years. This study presents data on the root development and architecture of 12 of New Zealand’s commonest early colonising indigenous shrub and tree species. These data are crucial to the development of guidelines and policy for land use conversion and future land management options where unmitigated erosion is of increasing concern. Methods: In a plot-based field trial, the growth performance of Coprosma robusta (karamū), Plagianthus regius (ribbonwood), Sophora tetraptera (kōwhai), Pittosporum eugenioides (lemonwood), Pittosporum tenuifolium (kōhūhū), Hoheria populnea (lacebark), Myrsine australis (māpou), Pseudopanax arboreus (fivefinger), Cordyline australis (cabbage tree), Knightia excelsa (rewarewa), Leptospermum scoparium (mānuka), and Coriaria arborea (tutu) was measured annually over five consecutive years. Results: Eleven species developed a heart-shaped root system and Cordyline australis, a tap-rooted system. By year 5, the root/shoot ratio ranged between 0.24 and 0.44, > 99.5% of the total root mass and root length of all species was confined to within 0.5 m of the ground surface and > 73% within 1 radial metre of the root bole. Regressions between root collar diameter (RCD over bark) and root length were highly significant (P < 0.001) (r2 values 0.55–0.92), as were regressions for root biomass (r2 values 0.31–0.97). RCD fitted best for below-ground biomass (r2 values 0.67–0.94). Conclusions: The species with the greatest potential for mitigating shallow forms of erosion were Pittosporum eugenioides, Plagianthus regius, Coriaria arborea, Pittosporum tenuifolium, Hoheria populnea, Sophora tetraptera, and Cordyline australis. New data on differences in root metrics between species have improved our understanding of their strengths and limitations, alone or as mixed plantings, and of the time (years after planting) and density of plantings required to achieve a successful erosion control outcome. Modelling root-soil reinforcement and the role of root systems in mitigating the initiation of shallow slope failures should include roots > 1 mm in diameter.

Pinus radiata D.Don has been established in a wide range of soils and climatic conditions, showing high variability in both leaf area and volume productivity. Previous research has shown that plantation yield is affected by water availability, but the majority of this work has been done in unthinned stands and provided little insight on the effect of water availability on the productivity of thinned plantations. In order to improve forest productivity for plantations under a climate change scenario, we must understand the effect of plantation management, including thinning on the relationships among available water, leaf area index, and productivity. The aim of this work is to evaluate the effect of site water availability on the leaf area production and consequent volume growth in thinned radiata pine plantations over a water availability gradient. Methods: The effect of site available water on leaf area production and consequent volume growth in thinned Pinus radiata plantations over a water availability gradient across five sites in central and southern-central Chile was determined. Results: Regression analysis revealed water deficit to be related to both leaf area index and volume growth accounting for 77 and 78% of the variation respectively. Eighty-one percent of the variation in volume growth was explained by the leaf area index. Results showed a growth efficiency of 5 m3 ha−1 per unit of leaf area index. Conclusions: Strong linear positive relationships between site water availability, leaf area, and stand growth after thinning found in this research suggest that water is the key factor controlling current productivity of radiata pine plantations across sites. A simple and robust water index that is well correlated with leaf area and stand annual volume growth allows for the construction of a simple predictive model that may support management decisions for radiata pine plantations.

Tree allometric equations are critical tools for determining tree volume, biomass and carbon stocks. However, there is a lack of species-specific biomass equations for juvenile trees of many of New Zealand’s indigenous species. The aim of this study was to provide allometric equations for total above- and below-ground biomass and total root biomass and length for eight common evergreen conifer and broadleaved species. Methods: In a plot-based field trial, growth metrics of conifers Prumnopitys taxifolia (matai), Agathis australis (kauri), Prumnopitys ferruginea (miro), Podocarpus totara (totara), Dacrycarpus dacrydioides (kahikatea) and Dacrydium cupressinum (rimu) and broadleaved species Alectryon excelsus (titoki) and Vitex lucens (puriri) were measured annually. These species were selected based on their potential role as a long-term solution for mitigating erosion in areas of marginal land proposed for new afforestation/reforestation and as an important carbon (C) sink. Results: Root collar diameter (RCD) provided the best fit for tree height, total above-ground biomass (AGB) and total below-ground biomass (BGB), and all regressions were highly significant (P = 0.001). Most species showed significant increases in annual growth and, by year 5, the BGB ranged between 21 and 42% of total biomass and decreased with increasing plant age. Of the conifers, Podocarpus totara had the greatest mean maximum root spread (2.2 m) exceeded only by the broadleaved Vitex lucens (2.5 m). For all species, and in each year of the trial, 100% of the BGB remained confined to within 0.5 m of the ground surface. With the exception of Vitex lucens and Podocarpus totara, > 90% of the total root length remained within a 0.5-m radius of the root bole. The species-specific mean tree biomass of 5-year-old plants ranged from 0.32 to 4.28 kg plant−1. A mixed-species forest established at 1000 stems per hectare (spha), consisting of 200 of each of the best performed of the trialled species, would amass ~ 2.3 t ha−1 of biomass and a forest carbon stock of 3.8 t CO2 ha−1 within 5 years. Conclusions: Inter-species differences in the allocation of BGB and AGB appeared to be age dependent. The root-growth metrics of these common indigenous forest species, as candidates for erosion control, have improved our understanding of their potential usefulness for stabilising marginal land. Whole-plant biomass of juvenile trees will greatly improve the accuracy of current estimates of forest carbon stocks for proposed new areas of indigenous afforestation/reforestation.

Douglas-fir comprises 6% of New Zealand’s planted forest area and contributes to the national carbon sequestration estimate. Carbon stock changes in Douglas-fir stem wood can be calculated by multiplying the increment in stem volume under bark by the density of the growth sheath and the carbon fraction. This paper describes a new model developed to predict variation in wood density of Douglas-fir growth sheaths from known wood density drivers. Methods: Datasets used to parameterise the wood density model contained: (1) mean breast height (1.4 m above ground) outerwood (based on 50 mm long cores) density of 30 trees per stand from 32 semi-mature and mature stands with soil and climate data, for predicting wood basic density from environmental factors; (2) basic density of wood samples taken at breast height and at regular height intervals along the stem of 75 trees from 10 stands, for predicting the weighted mean wood basic density of pre-defined growth sheaths; and (3) breast height pith-to-bark radial density profiles based on 500 trees from 47 stands, for predicting wood density of individual annual growth rings at breast height. Linear and non-linear mixed models were developed using these data to explain the variation in wood density of growth sheaths. Results: Breast height outerwood density was positively related to mean annual air temperature and negatively related to soil nitrogen fertility. This environmental model jointly explaining 83% of the variation in wood basic density at breast height of ring 30 from the pith. The radial pattern of wood density variation of annual growth rings at breast height was calibrated to a site using predictions from the environmental model. The ratio of growth sheath density to breast height ring density was applied to the predicted density of annual growth rings at breast height. This ratio decreased from 1.05 close to the pith to 0.95 in outerwood rings of mature trees, with ring number from pith explaining 49% of the variation in this ratio. Conclusions: A wood density model that incorporates the important drivers of variation in density of stem wood growth sheaths in New Zealand-grown Douglas-fir will improve the accuracy of carbon stock and stock change estimates in NZ’s planted forest estate. The new wood density model has been linked to the Forest Carbon Predictor which predicts carbon stocks in live and dead biomass pools from inventory plot measurements, site mean annual temperature, and soil nitrogen fertility information.

The Stakeholders in Methyl Bromide Reduction (STIMBR) are evaluating ethanedinitrile (EDN) as an alternative fumigant to methyl bromide for use as a phytosanitary treatment for pine logs (Pinus radiata D.Don). Ethanedinitrile is hypothesised to decompose into hydrogen cyanide (HCN) in the presence of water. This process, if it occurs, is of particular interest because it may influence the efficacy and emissions data needed for commercialisation. Methods: The concentrations of EDN and HCN were measured in the treated space (28 L fumigation chambers) without (n = 1) and with pine log sections (n = 3; 46 ± 1.4% load factor) at 10 or 20 °C in a simulated commercial fumigation. Results: On average, the cylinder of EDN tested contained 34.6 g m− 3 HCN (or 3.1%), which corresponds to a concentration of 0.8 g m− 3 (or 0.07%) in the treated space for a 50 g m− 3 EDN dose (commercial rate in Australia). This level of HCN is likely a result of the manufacturing process, whereby HCN is oxidised to produce EDN. During fumigation, HCN was detected in the treated space at relatively low concentrations, which did not significantly change over time. This indicates that HCN is not produced in substantial amounts during fumigation and that, as a result, insect efficacy is unlikely to be affected by low unchanging (P = 0.055) concentrations of this compound in the treated space. Conclusions: The results of this work support the statement that EDN is not significantly converted to HCN during the treatment of recently harvested pine logs.

Additional file 1 to 'Influence of climate on tree mortality in taiwania (Taiwania cryptomerioides) stands in Taiwan'

Additional file 2 to 'Influence of climate on tree mortality in taiwania (Taiwania cryptomerioides) stands in Taiwan'

Additional file 3 to 'Influence of climate on tree mortality in taiwania (Taiwania cryptomerioides) stands in Taiwan'

Taiwania (Taiwania cryptomerioides Hayata) is a relict tree species found mainly in Taiwan, with smaller populations in China, Vietnam, and Myanmar. Taiwania is considered to be vulnerable to extinction. The objective of this research was to develop a model to predict the mortality of taiwania from climate and other mensurational variables. Methods: The mensuration, mortality, and climate data came from permanent sample plots established as thinning experiments and a nearby climate station. The data were analysed using logistic regression with individual tree mortality as the response variable. Results: The important predictor variables of mortality were social status [defined as diameter at breast height (dbh) divided by average dbh] and annual precipitation in the year of death. The probability of mortality increased as social status decreased and as annual precipitation increased. The positive correlation between mortality and precipitation is likely a consequence of typhoons since precipitation and mortality caused by wind throw both result from typhoons. Conclusions: Climate change could increase the number and severity of typhoons occurring in Taiwan. This may increase the mortality rate of taiwania, which would detrimentally affect the viability of taiwania populations.

Concern is growing about the future of forestry productivity due to intensive nutrient removal, as a result of different harvesting operations. This study aimed to determine the effects on forest productivity when using different slash-retention scenarios with the recommended amounts of mineral fertiliser in Usutu forest. Usutu is a plantation forest that grows mostly softwood where the predominant species is Pinus patula Schiede ex Schltdl. & Cham. Methods: The first trial series (F) comprised of one trial located in each of five forest blocks. It was established in 1971 and compared the effects of various site preparation scenarios (slash removal, slash retention and cultivation) on the early growth of Pinus patula for adjacent first (F1R) and second rotation (F2R) sites (i.e. grassveld and clearfelled first-rotation sites). The second (S) trial series was re-established in April 1991 on exactly the same position as the first trial series, and involved second (S2R) and third rotation (S3R) sites. Three main treatments, standard pitting through harvest residue (control); manual pitting after removal of harvest residue and forest floor (cleared); and manual pitting and broadcast application of dolomitic lime (2 t ha− 1) over the slash (lime), were undertaken in factorial combination with the application of phosphate and potassium fertiliser. The data reported here are for tree volume productivity across the five sites of the first trial series up to age 10 years and three of the five sites of the second trial series up to age 9 years. Results: Slash removal decreased volume productivity by 9 and 13% in the F1R and F2R at 10 years of age and further by 21 and 33% in S2R and S3R, respectively at 9 years of age. However, fertiliser application increased volume productivity by 14 and 15% in the F1R and F2R at 10 years age and further by 18 and 10% in the S2R and S3R, respectively at 9 years of age. Conclusions: In order to sustain or increase productivity, it is recommended that harvest residue slash should be conserved and fertiliser containing phosphate and potassium be applied at planting at Usutu.

Gradients and disturbances affect plant communities. Cloud forests exist on elevational gradients and are often disturbed by being cleared for agriculture, so they present a unique opportunity for the investigation of how gradients and disturbances affect their structure, function and dynamics. The focus of the current study was on seed predation, seed pathogens and seed germination: all key factors in tree recruitment and regeneration. Methods: Three hundred seeds of three species—Solanum stenophyllum Bitter (Solanaceae: bird-dispersed), Palicourea amethystina (Ruiz & Pav.) DC. (Rubiaceae: bird-dispersed) and Clusia flaviflora Engl. (Clusiaceae: mammal-dispersed)—were studied at primary (1°) cloud forest at Guandera Reserve. After 2 weeks in the field, losses due to seed predation or pathogens were counted and the remaining seeds were tested for germination. These results were then compared with similar data collected and published previously from a 1° cloud forest and a secondary (2°) cloud forest, both at Maquipucuna Reserve, Ecuador. Results: In both closed-canopy forest and tree-fall gaps at Guandera Reserve, S. stenophyllum Dunal seeds suffered the greatest losses to predators, P. amethystina seeds had the greatest germination and C. flaviflora seeds had the greatest losses to pathogens. Comparison with data from Maquipucuna Reserve showed the following: (1) Solanum sp. suffered the greatest losses for seeds lost to seed predators in general but Cecropia sp. and Ficus sp. also had high losses in Maquipucuna 1° cloud forest; (2) for seeds lost to pathogens, species that lost the most seeds were unique to each study site: Clusia flaviflora seeds at Guandera 1° cloud forest, Cecropia sp. seeds at Maquipucuna 1° cloud forest and Piper aduncum L. seeds at Maquipucuna 2° cloud forest; (3) for seeds that germinated the most, species were again unique to the study site: Palicourea amethystina seeds at Guandera 1° cloud forest, Otoba gordoniifolia (A. DC.) A.H. Gentry seeds at Maquipucuna 1° cloud forest and Solanum ovalifolium Dunal seeds at Maquipucuna 2° cloud forest; and (4) in general, forest types differed significantly for both seed predation and seed pathogens. Within the 1° cloud forest at Maquipucuna, there was a significant difference among tree seed species for pathogens and a significant difference among the tree seed species for germination, and within the 2° cloud forest at Maquipucuna, there was a significant difference among tree seed species for pathogens. Conclusions: As elevation increases in 1° cloud forests, the proportion of seed that germinates remain largely constant, but the major seed loss shifts from being due to predators to being due to pathogens. Conversion to agriculture also leads to seeds mainly lost to predators, but individual species loss levels depended on what crop had been planted previously.

Eucalyptus species can be alternative plantation species to Pinus radiata D.Don (radiata pine) for New Zealand. One promising high value use for eucalypts is laminated veneer lumber (LVL) due to their fast growth and high stiffness. This study investigated the suitability of Eucalyptus globoidea Blakely for veneer and LVL production. Methods: Twenty-six logs were recovered from nine 30-year-old E. globoidea trees. Growth-strain was measured using the CIRAD method for each log before they were peeled into veneers. Veneer recovery, veneer splitting and wood properties were evaluated and correlated with growth-strain. Laminated veneer lumber (LVL) panels were made from eucalypt veneers only or mixed with radiata pine veneers to investigate the bonding performance of E. globoidea. Results: Veneers with no, or limited, defects can be obtained from E. globoidea. Veneer recovery (54.5%) correlated with growth-strain and was highly variable between logs ranging from 23.6% to 74.5%. Average splitting length in a veneer sheet was 3.01 m. There was a moderate positive association between splitting length and growth-strain (r = 0.73), but no significant association with wood stiffness (r = 0.27). Bond quality of LVL panels prepared using E. globoidea veneer and a phenol formaldehyde adhesive did not satisfy AS/NZ 2098.2. Conclusion: Usable veneers for structural products could be obtained from E. globoidea at yields of up to 74.5%, but variation in the existing resource (which has not been genetically improved) was large. In particular, growth-strain reduced veneer recovery by splitting, largely independent of stiffness. The considerable variation in growth-strain and stiffness indicated a possibility for genetic improvement. Furthermore, a technical solution to improve bonding of E. globoidea veneers needs to be developed.

In pine plantations, shading following canopy closure reduces the growth of competing vegetation. However, canopy closure is not always achieved if low initial planting density, pruning and thinning are practised. This means that complete shading does not occur, resulting in stands with potentially competitive levels of under-canopy vegetation. Methods: At the time of the first pruning operation, two trials were established to determine the competitive effect of under-canopy vegetation on pine tree growth in South Africa, one on a Pinus patula Schiede ex Schltdl. & Cham. (4.5 years) and one on a Pinus tecunumanii F.Schwerdtf. ex Eguiluz & J.P.Perry (2.9 years) stand. This paper documents results at the final thinning operation carried out at 17–18 years. Treatments were weedy (no vegetation control), herbaceous (complete sustained control of woody vegetation), woody (complete sustained control of herbaceous vegetation), weedfree (complete sustained control of all competing vegetation) and operational (only the woody perennial broadleaves were removed prior to any pruning/thinning event in the commercial weed control treatment). From the time vegetation management treatments were first imposed, they were maintained and tree performance monitored over 14–15 successive growing seasons, including and up to the second and final thinning to 250 stems ha−1. Results: The presence of vegetation for up to 15 years had no significant impact on the volume of P. patula and P. tecunumanii following two thinning operations (813 to 400 stems ha−1; 400 to 250 stems ha−1). For P. patula, but not P. tecunumanii, there was a significant and negative impact of under-canopy vegetation on the total basal area removed during two thinning operations. This may result in a reduction in the selection of stems to remain following thinning, as well as any profit that may be obtained if the thinnings were of commercial value. Conclusions: For the species (P. patula and P. tecunumanii) and sites tested, the results indicate that if good establishment weed control is carried out (from planting until the first pruning event), the development and subsequent impact of under-canopy vegetation over the subsequent 14–15 years (between the first pruning event and the final thinning to 250 stems ha−1) on the growth of the remaining stems is negligible.

In fast-growing forests such as Eucalyptus plantations, the correct determination of stand productivity is essential to aid decision making processes and ensure the efficiency of the wood supply chain. In the past decade, advances in remote sensing and computational methods have yielded new tools, techniques, and technologies that have led to improvements in forest management and forest productivity assessments. Our aim was to estimate and map the basal area and volume of Eucalyptus stands through the integration of forest inventory, remote sensing, parametric, and nonparametric methods of spatial prediction. Methods: This study was conducted in 20 5-year-old clonal stands (362 ha) of Eucalyptus urophylla S.T.Blake x Eucalyptus camaldulensis Dehnh. The stands are located in the northwest region of Minas Gerais state, Brazil. Basal area and volume data were obtained from forest inventory operations carried out in the field. Spectral data were collected from a Landsat 5 TM satellite image, composed of spectral bands and vegetation indices. Multiple linear regression (MLR), random forest (RF), support vector machine (SVM), and artificial neural network (ANN) methods were used for basal area and volume estimation. Using ordinary kriging, we spatialised the residuals generated by the spatial prediction methods for the correction of trends in the estimates and more detailing of the spatial behaviour of basal area and volume. Results: The ND54 index was the spectral variable that had the best correlation values with basal area (r = − 0.91) and volume (r = − 0.52) and was also the variable that most contributed to basal area and volume estimates by the MLR and RF methods. The RF algorithm presented smaller basal area and volume errors when compared to other machine learning algorithms and MLR. The addition of residual kriging in spatial prediction methods did not necessarily result in relative improvements in the estimations of these methods. Conclusions: Random forest was the best method of spatial prediction and mapping of basal area and volume in the study area. The combination of spatial prediction methods with residual kriging did not result in relative improvement of spatial prediction accuracy of basal area and volume in all methods assessed in this study, and there is not always a spatial dependency structure in the residuals of a spatial prediction method. The approaches used in this study provide a framework for integrating field and multispectral data, highlighting methods that greatly improve spatial prediction of basal area and volume estimation in Eucalyptus stands. This has potential to support fast growth plantation monitoring, offering options for a robust analysis of high-dimensional data.